I’m not talking about the title character of “Beetlejuice,” which opened Thursday night, but Eddie Perfect. Fresh off his heinous music for “King Kong,” the Australian composer’s dismal soft-rock score fuels one of the worst Broadway musicals in years.

Make that dismal and gross — like having his 15-year-old heroine sing about her love for “creepy old guys.”

The teenager burdened with that schlocky, long song is Lydia (Sophia Anne Caruso), a role made famous by a young Winona Ryder in the 1988 film that starred Michael Keaton. Lydia, her father, Charles (Adam Dannheisser), and his girlfriend, Delia (Leslie Kritzer), have just moved into a house they unknowingly share with the ghosts of the Maitlands. Barbara (Kerry Butler) and Adam (Rob McClure) perish after falling through the floor of their fixer-upper, only to return as novices in the afterlife: inexperienced and dumb.

The couple loathes the new tenants — Delia, an obnoxious life coach, is turning their charming country home into the Museum of Modern Art — so they call on Beetlejuice, a “bio-exorcist,” to do his dirty work and chase the interlopers out.

Trouble is, we met Beetlejuice some 40 minutes before, so there’s no buildup or suspense. Alex Brightman arrives in the opening number as an annoying, lowbrow narrator who lacks Keaton’s sly, unwashed trucker charm. You get sick of this Beetlejuice fast, especially since Brightman plays him like a drug-addicted Krusty the Clown — snorting cocaine off his forearm, making erection jokes and dropping F-bombs. Leave the kids at home.

The other wrong turn the show makes is Lydia’s motivation. Here, her goth attire and obsession with the supernatural are a direct — and oft-stated — response to her dead mom. She even sings a song about it called . . . “Dead Mom.” The Maitlands and Beetlejuice, Lydia thinks, can bring her to the netherworld to see her mother once more. This sappy subplot robs the musical of macabre and fits the story as well as O.J.’s glove.

Most of the cast overplays (Butler, Kritzer) or underplays (McClure, Dannheisser), but the talented Caruso, with a Cyndi Lauper-like voice, strikes the right balance. This is a challenge for all involved, especially in the second half of Scott Brown and Anthony King’s jumbled book.

Indeed, if the actors took their scripts, threw them into the air, picked up the pages and performed them in their new order, Act 2 would be about the same. Director Alex Timbers’ hyperactive staging and David Korins’ huge-but-ugly set don’t help matters much.

The musical’s best and clearest moments happen to be the excellent movie’s best: “Day-O (The Banana Boat Song)” when the Maitlands attempt to scare the living by making them sing and dance; and the upbeat “Jump in the Line (Shake, Señora).”

And so ends the largely awful 2018-19 season. This summer, Broadway needs an exorcism.